A capability to process a stream of randomly cyclic and variable data on the fly, substantially in real time, may permit one to timely determine relative maximum and minima. Such a substantially real time processing capability may also permit one to determine, sort out, and match the hierarchy of extrema (i.e., maxima or minima), greatest positive and negative excursions of the data; to determine the magnitude of each excursion set of substantially matched positive extrema and negative extrema; to determine the duration of each excursion set; and to determine mean amplitude value for each excursion set.
A determining, sorting out and matching hierarchy of signal or data excursions may be effected using the Matsuishi-Endo Rainflow Counting Method. The Rainflow Counting Method is believed to have been first published in Japanese in 1968. A good English-language description of the Rainflow Counting Method may be found in Metal Fatigue in Engineering; by Ralph I. Stephens, Ali Fatemi, Robert R. Stephens and Henry O. Fuchs, John Wiley & Sons, New York; 2001, pp. 281-286. The Rainflow Counting Method has been implemented in various ways to effect counting cyclic signals representing data and sorting out a history of “peaks and valleys” occurring in a stream of data. However, all implementations to date involving the Rainflow Counting Method are believed to have involved after-the-fact implementations of the method using data relating to a completed test or other generation of data. No implementation is known to have been effected for carrying out a substantially real time, on the fly, evaluation of a time varying signal, including a substantially real time sorting of peaks and valleys in a time varying signal.
There is a need for a method and apparatus for effecting substantially real time evaluation of a time varying signal that permits selection and extraction of relative maxima and minima (i.e., extrema) from the signal.
There is a need for a method and apparatus for effecting substantially real time evaluation of a time varying signal that permits substantially real time presentation of pertinent characteristics of the signal such as, by way of example and not by way of limitation, signal magnitudes, signal cycle durations and mean signal amplitudes.